Radial blowers are used for applying air streams to sieves and optionally to cascading sieves in the cleaning devices of self-propelled combine harvesters. The air stream allows a separation of the heavy grains from lighter particles, such as chaff, and it should have as-even-as-possible an intensity over the width of the cleaning device, so that the desired cleaning effect can be achieved over the entire width of the sieves.
Besides radial blowers with a housing that extends over the width of the cleaning device in which several paddles attached on a rotating shaft are circumferentially offset from each other (DE 504 189 A), or with paddles that extend nearly over the width of the housing (EP 1 389 416 A), radial blowers have been proposed that consist of several component blowers arranged next to each other in separate housings. The component blowers comprise paddles arranged on a shaft that passes through all the housings. The housings have lateral inlet openings that are adjacent to the shaft and wind ducts that radially from the paddles towards the cleaning device.
Such a radial blower is described in DE 29 22 607 C. The side walls of the wind ducts extend in a straight line outward and form an obtuse angle with the lateral housing walls in each case, so that the cross section of the wind ducts broadens to form a funnel toward the cleaning. Adjacent side walls of the wind ducts are connected to each other by short front walls. The front walls are absent in DE 24 23 917 A and U.S. Pat. No. 2,954,123 A because there the side walls of the wind ducts are connected directly to each other.
In DE 14 03 495 A, which is considered to be the generic case, the side walls of the wind ducts broaden outward in the shape of an S. The side walls of the wind ducts are connected with a convex curvature to the side walls of the housing of the component blower. The convex curvature then transitions, approximately in the middle of the length of the side walls of the wind ducts, into a concave curvature, so that the mentioned S shape is produced. The front walls are omitted because the ends of the side walls are connected directly to each other. This arrangement is said to have been designed using fluidics.
To further improve the evenness of the transverse distribution of the intensity of the wind, DE 102 46 858 A proposes to extend the side walls of the wind ducts in a straight-line extension of the side walls of the associated blower housing, and to connect the adjacent side walls of the wind ducts to each other by a front surface that extends at a right angle from the side walls of the associated blower housing. In embodiments, radii are provided in the connection area between the side walls of the wind ducts and the front wall, or the front surface is designed in a shape of an arc of a circle.